District Judge E. Wayne Phillips issued a 78-page ruling siding with state officials and conservation groups that have sought to ease restrictions on bison movements.

Thousands of bison flood out of Yellowstone during severe winters. In the past, the animals were subject to mass slaughters over fears they could spread the disease brucellosis to livestock.

The slaughters were blocked by former Gov. Brian Schweitzer two winters ago after cattle numbers declined outside Yellowstone and federal officials reduced the penalties for states that have brucellosis outbreaks.

But when hundreds of bison were allowed to return to the Gardiner Basin, local officials said they posed a threat to safety and destroyed private property.

Park County and groups representing ranchers sued the state in 2011 with a pair of lawsuits that sought to keep bison out of the basin.

Attorneys for the plaintiffs argued the animals were a threat to public safety and their presence outside the park increased the risk of disease.

In his ruling, Phillips acknowledged the plaintiffs' struggles with bison, but said those were an unavoidable consequence of living in Montana with its abundant wildlife.

State officials "do not have a statutory duty to ensure that no harm is incurred by a Montana resident by a wild animal," he said.

He added that damage done by bison to fences and other private property in the Gardiner Basin "does not rise to the level of an interference that is both substantial and unreasonable."

A lawyer representing conservationists who intervened in the case said the ruling was crucial to efforts to make more room for the animals outside the park.

"This was a key test of the question of will Montana make room for bison," said Tim Preso, an attorney for the group Earthjustice. "After decades of hazing and slaughtering bison ... the state saw there was a better way forward."

Park County Attorney Brett Linneweber said the plaintiffs have 60 days to decide whether to appeal to the Montana Supreme Court.

But Linneweber said it was "nonsensical" to believe more bison in areas where people live would not pose a danger to the public. He also criticized the state for disregarding more acceptable alternatives, such as transporting bison that leave the park to American Indian reservations.

He warned that the expansion of the bison's range will continue regardless of local community concerns.

The state has advocated relocating some Yellowstone bison to reservations and public lands, and last year moved a small batch of the animals to the Fort Peck Indian Reservation in eastern Montana. Those efforts have been fiercely fought by ranching groups and others.

Linneweber said he would have to confer with the county's co-plaintiffs, the Montana Farm Bureau Federation and Park County Stockgrowers Association, before deciding whether to appeal.

Farm Bureau president Bob Hanson said in a statement that his group was disappointed in the ruling. Hanson called on the state Legislature to act on the issue "to protect Montana's livestock industry."

Montana Fish, Wildlife and Parks spokesman Ron Aasheim said the ruling was a victory for the state.

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